1. Technical Field
The present invention relates generally to illuminating apparatuses, and particularly to an illuminating apparatus using principles of natural ventilation for improving heat dissipation efficiency.
2. Description of Related Art
With the continuing development of scientific technology, light emitting diodes (LEDs) have been widely used in the field of illumination due to its high brightness, long service lifetime, wide color gamut and so on. Relevant subject matter is disclosed in an article entitled “Illumination With Solid-state Lighting Technology”, published on IEEE Journal on Selected Topics in Quantum Electronics, Vol. 8, No. 2, authored by Daniel A. Steigerwald et al. in March/April, 2002, the disclosure of which is incorporated herein by reference.
LEDs generally emit visible light at specific wavelengths and generate a significant amount of heat. Generally, approximately 80-90% of the power energy consumed by the LEDs is converted to heat, with the remainder of the power energy converted to light. If the generated heat cannot be timely removed, LEDs may overheat, and thus their performance and service lifetime may be significantly reduced.
Referring to FIG. 11, U.S. Pat. No. 7,144,135 discloses an LED lamp 10 which includes an exterior shell 11 and an interior, an optical reflector 12 disposed in the shell 11. The shell 11 and the optical reflector 12 define a space therebetween for severing as an air channel 13 to cool the LED lamp 10. The shell 11 has a truncated conical shape which defines an opening 111 at a wider end thereof. A narrower end of the shell 11 is connected to an AC/DC converter 15. The narrower end of the shell 11 defines a plurality of air vents 16 for severing as air intake holes for the LED lamp 10. An LED 14 is located at the bottom end of the optical reflector 12 and mounted to a heat sink 17. The heat sink 17 is disposed in the shell 11. A motor 18 is mounted to a bottom of the heat sink 17 for severing as drive a fan 19. The fan 19 moves air over the heat sink 17 from the plurality of air vents 16 and through the air channel 13 defined between the shell 11 and the optical reflector 12 and flowing outside the LED lamp 10 for heat dissipation.
However, when the motor 18 operates, additional energy is required to drive the motor 18. This is not favorable to save energy. In addition, a probability of malfunction of the LED lamp 10 will be increased due to the use of the motor 18 and the fan 19.
What is needed, therefore, is an illuminating apparatus which can overcome the above-mentioned disadvantages.